Get this PocketWizard NMCDC2P, normally $85.00, on sale at $72.25 for a total savings of $12.75.
This N-MCDC2-P PocketWizard cable is designed exclusively for the Nikon D90's and D5000 unique 4-pin connector.
Like all current pre-trigger cables, this is designed to keep a camera "awake," the same as pressing the camera's shutter button halfway down. Keeping the camera in the "awake" mode shortens the button-press-to-shutter-release lag time dramatically. However, it will also use more of the camera's battery. A control box in the cord enables switching the pre-triggering mode ON and OFF.